1. Field of the Invention
The present invention relates to a collapsible telescopic steering apparatus.
2. Description of Related Arts
In collapsible steering apparatuses adapted for shock absorption during a vehicle collision, inner and outer tubes of a steering column are press-fitted to each other so as to absorb a shock upon vehicle collision.
The inner and outer tubes press-fitted to each other are not moved relative to each other under a normal load, but are slid relative to each other by an impact force exerted thereon during a vehicle collision to absorb a shock.
On the other hand, it is demanded to provide a telescopic adjustment function for adjusting the fore-and-aft position of a steering wheel along the axis of a steering shaft in accordance with the desires of a driver.
To meet the demand, the inventor of the present invention has contemplated to incorporate a telescopic adjustment mechanism in the aforesaid collapsible steering apparatus, wherein the telescopic adjustment mechanism is adapted to slide the inner and outer tubes of the steering column relative to each other to extend or contract the steering column for telescopic adjustment. However, such an arrangement is not feasible.
This is because it is necessary to press-fit the inner and outer tubes to each other for shock absorption but it is impossible to slide the press-fitted inner and outer tubes relative to each other by manually applying a normal operation load to the tubes.
Hence, there is no other way but to employ a telescopic adjustment mechanism of a type which is adapted to move the entire steering column for the telescopic adjustment. However, the telescopic adjustment mechanism of this type requires a greater clearance for moving the entire steering column, so that the size of the steering mechanism is increased.